2007/10/30, Wolfgang Werners-Lucchini <wwl@musensturm.de>:
Sorry, I don't understand what the problem is!

It is related to ConTeXt's multicolumn Output Routine.

> > I have a problem with
> >
> > \startitemize[columns,a]
> > \item $a_n=2+\frac{1}{n+1}$
> > \item $a_n=\frac{(-1)^n}{\sqrt{n}}-3$
> > \stopitemize
> >

> Hi,
>
> this did not wotk because the second formula is than the first and
-------------------------------------------------^ (what?)

> the multicolumn OTR tries to put half or less of the text into the
> second column, you can now force a second column with the \column
> command after the first line or you switch both
> formulas and the OTR can make two columns.
>
> \starttext
>
> \startitemize[columns,a]
> \item $a_n=\frac{(-1)^n}{\sqrt{n}}-3$
> \item $a_n=2+\frac{1}{n+1}$
> \stopitemize

Why is this working? Here the first column is as big as the second
above (same formula), so the same problem should arise with the first
column as above with the second?

No, they are not, the first row (column) is 1 points taller than the second
one, you can test this with TeX.

\starttext

\setbox\scratchbox\hbox{$a_n=\frac{(-1)^n}{\sqrt{n}}-3$}

Formula 1: \copy\scratchbox

Height of formula 1: \the\ht\scratchbox

\setbox\scratchbox\hbox{$a_n=2+\frac{1}{n+1}$}

Formula 2: \copy\scratchbox

Height of formula 2: \the\ht\scratchbox

\stoptext

> \startitemize[columns,a]
> \item $a_n=2+\frac{1}{n+1}$ \column
> \item $a_n=\frac{(-1)^n}{\sqrt{n}}-3$
> \stopitemize

Why does the \column help with the first formula?

Because  itemize use for the columns key the  multicolumns envrionment
where you can force a new column with the \column command.

The internal work for this case is something like in the following example:

\starttext

\startcolumns
$a_n=\frac{(-1)^n}{\sqrt{n}}-3$

$a_n=2+\frac{1}{n+1}$
\stopcolumns

\startcolumns
$a_n=2+\frac{1}{n+1}$ \column

$a_n=\frac{(-1)^n}{\sqrt{n}}-3$
\stopcolumns

\stoptext

No, I don't understand this at all.

I hope my examples helped you a little bit to understand the problems
in your example and why my methods worked.

Wolfgang